Interference between wave modes may contribute to the apparent negative dispersion observed in cancellous bone
Interference between wave modes may contribute to the apparent negative dispersion observed in cancellous bone
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DOI：
10.1121/1.2953309
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发表时间：
2008-09-01
影响因子：
2.4
通讯作者：
Miller, James G.
中科院分区：
文献类型：
--
作者：
Anderson, Christian C.;Marutyan, Karen R.;Miller, James G.
先前的研究表明，超声波通过松质骨的传播通常表现为线性频率衰减系数，但相速度随频率下降（负色散），这与因果关系强加的Kramers-Kronig关系不一致。在目前的研究中，类似于在骨中观察到的干扰波模式被证明可能有助于观察到的负色散。利用Biot理论、改进的Biot- attenborough模型和实验结果来模拟多模波在松质骨中的传播。模拟需要使用合理的速度和振幅构建显示正色散的单个波模式，然后将单个模式相加以创建混合模式输出波形。模拟结果表明，在假设只有一个波存在的情况下，混合模式波形可以表现出负色散，即使单个干涉波表现出符合Kramers-Kronig关系的正色散。此外，当时域数据中存在很少或没有干扰的视觉证据时，观察到负色散。了解导致观察到的负分散的机制可以帮助确定松质骨的真实材料特性，而不是使用传统数据分析技术测量的表面特性。(C) 2008美国声学学会。
Previous work has shown that ultrasonic waves propagating through cancellous bone often exhibit a linear-with-frequency attenuation coefficient, but a decrease in phase velocity with frequency (negative dispersion) that is inconsistent with the causality-imposed Kramers-Kronig relations. In the current study, interfering wave modes similar to those observed in bone are shown to potentially contribute to the observed negative dispersion. Biot theory, the modified Biot-Attenborogh model, and experimental results are used to aid in simulating multiple-mode wave propagation through cancellous bone. Simulations entail constructing individual wave modes exhibiting a positive dispersion using plausible velocities and amplitudes, and then summing the individual modes to create mixed-mode output wave forms. Results of the simulations indicate that mixed-mode wave forms can exhibit negative dispersion when analyzed conventionally under the assumption that only one wave is present, even when the individual interfering waves exhibit positive dispersions in accordance with the Kramers-Kronig relations. Furthermore, negative dispersion is observed when little or no visual evidence of interference exists in the time-domain data. Understanding the mechanisms responsible for the observed negative dispersion could aid in determining the true material properties of cancellous bone, as opposed to the apparent properties measured using conventional data analysis techniques. (C) 2008 Acoustical Society of America.